Appearances:

Gorgons looked like blue, ethereal serpents. Each Gorgon was composed of several of these serpentine forms. They could hiss but not speak. They had some telepathic powers, specifically mind control.

Gorgons petrified creatures within a matter of hours. To do so, they needed to leave their host and make contact with the target. They could be reflected by a mirror, causing them to return to the host and turning it to stone.

Gorgons were a species of parasites, inhabiting the bodies of creatures like humans. While in the host, they greatly increased its lifespan, letting one human host live for over two hundred years. This was much less than the Gorgon's natural lifespan of thousands of years, which meant they had to frequently switch hosts. (TV: Eye of the Gorgon)

The third Gorgon eventually inhabited the body of an abbess and led the sisterhood of nuns at St Agnes Abbey, manipulating their minds to serve it for more than two centuries. The Gorgon sent the nuns to retrieve the talisman, planning to call the Gorgons from their home world to invade Earth and take all of humanity for their hosts. The Gorgon was defeated by Sarah Jane, Luke, Maria and Clyde, using a mirror to defeat the Gorgon whilst trying to possess Sarah Jane as a new host. (TV: Eye of the Gorgon)

In 2008Mr Smith mentioned that some lifeforms would survive after being turned into stone by a Gorgon. The bodies of Humans and silicon-based lifeforms like the Ogri of Ogros and the then extinct Kastrians of Kastria weren't compatible with being turned to stone. (WC: The Gorgon)